1. Mary Lou Dunzik-Gougar, PhD ANS Teachers’ Workshop 2013
The Nuclear Fuel Cycle
Mary Lou Dunzik-Gougar, PhD
ANS Teachers’ Workshop
2013

3. Uranium Mining Open pit (strip) mining In situ leaching
Underground mining

5. Uranium Milling Ore is crushed Uranium is separated
U3O8 “yellow cake” produced

7. Uranium Conversion (to UF6 gas)
Impurities removed
Uranium combined with fluorine
UF6 gas produced
- Gaseous form facilitates
enrichment
UF6 containers

9. U Enrichment Natural U is > 99% 238U and only ~ 0.7% 235U
Separation of 235UF6 and 238UF6 based on (very small) mass difference
UF6 enriched from 0.7% 235U to 3%-5% 235U
Diffusion
Centrifugation

11. Fuel Fabrication
Enriched UF6 gas converted to uranium oxide (UO2) solid
Finally, the uranium hexafluoride is shipped to a fuel fabricator, where it is manufactured into solid ceramic pellets, about the size of the end of a finger.
Uranium Oxide Ceramic Fuel Pellets

12. Fuel Fabrication Fuel rods filled with ceramic pellets are
grouped into fuel assemblies

13. Fuel Fabrication
A pressurized water reactor fuel assembly

15. Reactors
Diablo Canyon nuclear power plant in the U.S.

17. In the reactor, 235U fissions to produce . . .
Neutrons
Energy
Fission Products
Neutron
Neutrons may
Cause new fissions to occur
Be absorbed to form unstable, radioactive nuclide

18. Fuel Consumption in the Reactor
Fuel is in reactor for 4 – 6 years
U consumed, fission products and transuranics (mostly Pu) produced
Fresh Fuel 4%
96%
235U
I like to talk about this in a simple way as: things lighter than U <---> U <---> things heavier than U
238U Pu
3.5%
94%
Used Fuel
Fission
Products
Transuranics
(or Actinides)

19. Radioactive Decay Equations
Alpha Decay
Beta Decay
Gamma Decay
238 92 U
234 90
Th + 4 2 a 38 Sr 39
Y + -1 b
60m 56 Co 60
Co + g + n
Fuel isotope
Fission product
Fission product

20. Sources of radiation The average American receives a
Source: National Council on Radiation Protection and Measurement Report 160 (2006)
The average
American receives a
radiation dose of 620 millirem per year.
Nuclear Power
(<0.1%)
Human Body
(5%)
Cosmic
Consumer Products
(2%)

21. Units of Dose and Exposure
Roentgen (R) - unit of exposure - ionization of air by x or gamma rays
RAD (Radiation Absorbed Dose) - energy deposited in material (Gray (Gy) is international unit)
rem - (Roengten Equivalent Man)
unit of dose equivalent
Seivert (Sv) is international unit

22. Units of Radioactivity
Activity - a rate; the number of emissions (of radiation) per unit time.
dps - disintegrations per second
Bequerel = 1 dps
Curie = 37,000,000,000 dps
Picocurie = dps or 2.2 dpm

24. Used Nuclear Fuel Storage
Used fuel first stored in pool at least 5 years
Cooling and shielding
Older fuel can move to dry casks
Air cools
Steel and concrete shields

26. Fuel recycle/reprocessing
Fresh Fuel 4%
96%
235U
238U Pu
3.5%
94%
Used Fuel
Fission
Products
Transuranics
(or Actinides)

27. Fission products and non-Pu TRUs
Fuel recycle/reprocessing
Used fuel U
Re-enrichment Pu
New fuel
Fission products and non-Pu TRUs
Vitrified Waste

29. Geologic Repository The choice of countries worldwide
U.S. has studied Yucca Mt., Nevada as potential location

30. The Three C's of Used Nuclear Fuel
Compact....
Suppose
You live for 80 years
All electricity is nuclear
Your share of used nuclear fuel

31. The Three C's of Used Nuclear Fuel
Compact.... Contained....
Solid fuel pellet, inside...
Metal fuel rod, inside...
Steel canister, inside...
Storage or shipping cask

32. The Three C's of Used Nuclear Fuel
Compact.... Contained.... Cared for....
Carefully tracked
Decades of safe handling experience
Easy to detect and monitor
Paid for in Nuclear Waste Fee

33. The End . . .